MAINTENANCE OF M939 SERIES VEHICLES - OD1661 - LESSON 1/TASK 1
on the highway. They can also haul additional trailer loads of up to
15,000 pounds cross-country and 30,000 pounds on highways. The M935
expansible van is equipped with a hydraulic liftgate (W/HLG).
This
feature makes it the preferred vehicle to use when heavy, electronic
equipment must be moved in or out of the van.
(3) Performance. The maximum speed of M934 vans is 53 miles per
hour. Under maximum loads, both vans climb road grades as steep as
22. Without trailer loads, they can handle grades up to 33. Fully
loaded, the maximum cruising range is 300 miles per tank of fuel.
Without the trailer load, the van cruising range is 350 miles per
tank.
Both vehicles can ford hard-bottom water crossings up to 30
inches without a deepwater fording kit and 78 inches with the kit.
Both the M934 and M935 expansible vans have a turning radius of 45
feet 2 inches.
(4)
Special Limitations.
(a) Vans must be positioned on firm or near-firm soil before
expanding the sides.
(b) The hydraulic liftgate cannot raise equipment weighing more
than 3,000 pounds.
3.
Technical Principles of Operation
a.
General.
These paragraphs explain how components of the 5 ton
M939 series vehicles work together.
A functional description of
these components and their related parts is covered next.
b.
Engine.
The M939 family of vehicles use the NHC 250 engine.
This engine is a diesel powered, naturally-aspirated, liquid cooled 6
cylinder engine capable of producing 250 brake horsepower at 2100
rpm.
Idle speed for the engine is 600-650 rpm, with an operating
speed of 1500-2100 rpm. The engine produces 15 psi of oil pressure
at idle speed and 55-75 psi at operating speed. When the engine is
operating at normal operating temperature, the engine operates
between 175 F to 195 F. The engine averages 3 to 4 miles per gallon
of fuel.
c.
Cooling
System.
The
cooling
system
is
equipped
175
with
a
thermostat
that
begins
to
open
at
F
and
should
be
fully
open
when
the
engine
temperature
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